The purpose of the proposed work is the development and improvement of techniques for determining trace elements in samples of biological or clinical interest. Specific projects are directed toward one or more of the following goals: (1) improved understanding of fundamental principles governing atomic spectroscopy and its application to analysis, (2) development or improvement of instrumentation for analytical atomic spectroscopy, (3) translation of developments and improvements in theory or instrumentation into improved methods of analysis. Projects in progress include an investigation of the utility of a stabilized are device for trace analysis, studies relating to computer optimization of complex instrumental systems, and development of atomic fluorescence methods for the determination of selected elements in complex samples.